Hub 3 / Compal CH7465-LG (TG2492LG) and CGNV4 Latency Cause

[Datalink]

Good Day Ladies and Gentlemen,

Greetings from the other side of the pond, so to speak.  Over the last few weeks I've been perusing various user forums across North America and Europe for issues related to Intel Puma 6 modem latency.  Of those forums, your Hub 3 stands out as yet another Puma 6 based modem where users see continuous latency no matter what site is used or what online game is played. Considering all of the problems that are on the go, the following information should be of interest to all Hub 3, Compal CH7465-LG and Hitron CGNV4 modem users.  There is much more to post regarding this, so this is a start, to alert VM users as to the real cause of the latency and hopefully engage the VM engineering staff, via the forum staff, with Arris.  I am surprised to see that there has been no mention on this board of users from other ISPs who are suffering the exact same issues with their modems, so, this may come as a surprise to some, and possibly old news to others.

So, the short story ........

The Hub 3 / Compal CH7465-LG (TG2492LG) & Hiton CGNV4 modems are Intel Puma 6 / 6 Media Gateway (MG) based modems.  These modems exhibit high latency to the modem and high latency thru the modem.  The latency affects all IPV4 and IPV6 protocols, so it will be seen on every internet application and game.  The basic cause is the processing of the data packets thru a CPU software based process instead of thru the hardware processor / accelerator.  It appears that a higher priority task runs periodically, causing the packet processing to halt, and then resume.  This is observed as latency in applications and in ping tests to the modem and beyond.  For the last several weeks, Hitron, along with Intel and Rogers Communications in Canada have been addressing the latency issue within the Hitron CGNxxx series modems.  To date, only the IPV4 ICMP latency has been resolved.  Although this is only one protocol, it does show that a Puma 6MG modem is capable of using the hardware processor / accelerator with good results.  Currently Rogers is waiting for further firmware updates from Hitron which should include an expanded list of resolved protocol latency issues.  For Arris modems, "Netdog" an Arris engineer indicated last week that Arris was onboard to address the issue for the Arris SB6190 modem.  That should be considered as good news for any Arris modem (read Hub 3) user as Arris should be able to port those changes over to other Puma 6/6MG modems fairly quickly.  This is not a trivial exercise and will probably take several weeks to accomplish.  Note that there is no guarantee at this point that it is possible to shift all packet processing to the hardware processor / accelerator without suffering from any packet loss side effects.  Time will tell if all of the technical issues can be resolved with the current hardware included in the Puma 6/6MG chipset.  Last night, Netdog loaded beta firmware on selected test modems on the Comcast Communications network.  As this was only done last night, it's too soon to tell what this version resolves and if it was successful or not.  Netdog has contacts with staff at Comcast, Rogers, Charter and Cox Communications to fan out beta versions and modifications for testing.  I'd say its time to add Virgin Media and/or Liberty Global to that group as well.

Recent activity:

Approx three weeks ago a DSLReports user, xymox1 started a thread where he reported high latency to an Arris SB6190 and illustrated that with numerous MultiPing plots.  This is the same latency that I and other users with Rogers communications have been dealing with for months so it came as no surprise.  As well as reporting via that thread, xymox1 took it upon himself to email several staff members at Arris, Intel, Cablelabs and others.  The result of that campaign was Netdog's announcement, last week, that Arris was fully engaged at resolving the issue.  That has led to last nights release of beta firmware, although as I indicated its too early to determine what the beta firmware resolves, if anything.

The original thread that xymox1 started is here:

https://www.dslreports.com/forum/r31079834-ALL-SB6190-is-a-terrible-modem-Intel-Puma-6-MaxLinear-mis...

Yesterday, DSLReports issued a news story covering the thread:

https://www.dslreports.com/shownews/The-Arris-SB6190-Modem-Puma-6-Chipset-Have-Some-Major-Issues-138...

Today, Arris responded:

https://www.dslreports.com/shownews/Arris-Tells-us-Its-Working-With-Intel-on-SB6190-Puma6-Problems-1...

That response was also picked by Multichannel.com

http://www.multichannel.com/news/distribution/intel-arris-working-firmware-fix-sb6190-modem/409379

This is more news likely to appear in the next few days as additional tech and news staff pick up on this issue.

Hub 3 observations:

Like many others using a Puma 6/6MG modem, Hub 3 users are experiencing latency when they ping the modem, or ping a target outside of the home, game online or use low latency applications.  The common misconception is that this is Buffer Bloat. It's not. Its most likely a case of the packet processing stopping while the CPU processes a higher priority task.  The packet processing is done via the CPU no matter what mode the modem is operating in, modem mode or router mode and no matter what IPV4 or IPV6 protocol is used.  Normally, the latency is just that, latency.  The exception are UDP packets. In this case there is latency and packet loss.  The result of that is delayed and failed DNS lookups, and poor game performance for games that use UDP for player/server comms or player/player comms.

Can this be fixed?

So far, it appears that the answer is yes.  Rogers Communications issued beta firmware to a small group of test modems in October.  This version shifted the IPV4 ICMP processing from the CPU to the hardware processor / accelerator, resulting in greatly improved performance in ping latency.  At the present time we are waiting for the next version firmware which should shift other protocols over to the hardware processor / accelerator.  That can be seen in the following post:

http://communityforums.rogers.com/t5/forums/forumtopicpage/board-id/Getting_connected/message-id/369...

The details and results of last nights beta release to the Comcast group have yet to be seen.

At this point there is enough reading to keep most staff and users busy.  My intention is to post some of the history leading up to this point and instructions on how to detect the latency and packet loss.  This is not thru the use of a BQM.  I had hoped to post this all at once but events are moving much faster than I had thought they would.  For now this should suffice to get the ball rolling.

Below is a link to a post with a couple of HrPing plots from my 32 channel modem to the connected CMTS.  This shows the latency that is observed and reflects what others have posted in this forum using Pingplotter and HrPing.

https://www.dslreports.com/forum/r31106550-

HrPing is one of the freebie applications that can be used to monitor the latency to and thru the modem. 

Pingplots with Pingplotter which show the latency from my modem to the CMTS can be found in the first two to three rows of my online image library at Rogers Communications, located below.  They are essentially what the BQM would look like if you were able to zoom into the plot to the point where you could see the individual ping spikes.  Those ping spikes are common to Puma 6 and Puma 6MG modems.

http://communityforums.rogers.com/t5/media/gallerypage/user-id/829158

 [MOD EDIT: Subject heading changed to assist community]

[jonathanm]

That sounds like something different as max. download/throughout typically isn't affected by this issue and is more likely hardware fault or external factor. If it's a Hub3 you hav then the latency on ping will be happening, but not on week ICMP request/response and won't be restricted to certain days.

According to posts before Christmas the new firmware should be being rolled out any day now 😄. Anyone any news on this?

[tommey]

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@jonathanm wrote:


According to posts before Christmas the new firmware should be being rolled out any day now 😄. Anyone any news on this?

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Who cares about a new firmware that just masks the problem from BQM's?

[Guybrush85]

Can I just say that this 'mask' nonsense is just that... nonsense. Virgin didn't develop this to try and hide the behaviour, this was done by Arris/Intel and is actually a fix to ICMP traffic moving it to the Packet Processor and was done before TCP/UDP/ARP etc etc was known to be an issue.

The fix also fixes UDP DNS and there are other things in there, which I can't comment about as they're not publicly talked about, so yeah, it's worth having, albeit not a complete fix. 

At least it will stop people posting pings and BQM's all the time  *ahem* 

[horseman]

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Guybrush85 wrote:.....Virgin didn't develop this to try and hide the behaviour, this was done by Arris/Intel and is actually a fix to ICMP traffic moving it to the Packet Processor and was done before TCP/UDP/ARP etc etc was known to be an issue.

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........At least it will stop people posting pings and BQM's all the time  *ahem* 

However some TCP/UDP resource issues (and specifically ARP cache/timeout issues) were reported during past SuperHub testing back in at least 2013 so before SH2AC Trials and current SH3 Puma6/ICMP BQM hysterics.  

As VM (public limited Beta Trials) were restricted (and in fact an ARP issue was recorded on first SH2/VMDG485 just after Apr2013 but the forum has been subsequently deleted) then we can't publish any proof (or absence to contrary) of what was forwarded via Netgear and/or to Texas/Intel other than some replies from VM CPE Firmware group that essentially(paraphrased) said the issues were "a limitation and commensurate with cost/limitations of a (implied cheap and cheerless) domestic router".    😛

That's why (after the previous SH/VMDG280, SH1/VMDG480 debacles in 2009/10) the usual user community began emphasising that VM Hubs were "get you going cheap starter devices and to use ModemMode and 3rd party routers to provide additional functionality"

Obviously there's always a "balance" between "cost/time" of both hardware and firmware versions in addressing/resolving functional and usability issues on all hubs which is why I suspect last public firmware release of SH3 9.1.116V halted back in mid 2016. 

[Guybrush85]

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@horseman wrote:

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Guybrush85 wrote:.....Virgin didn't develop this to try and hide the behaviour, this was done by Arris/Intel and is actually a fix to ICMP traffic moving it to the Packet Processor and was done before TCP/UDP/ARP etc etc was known to be an issue.

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........At least it will stop people posting pings and BQM's all the time  *ahem* 

However some TCP/UDP resource issues (and specifically ARP cache/timeout issues) were reported during past SuperHub testing back in at least 2013 so before SH2AC Trials and current SH3 Puma6/ICMP BQM hysterics.

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Interesting! I didn't know about that, so you certainly learn something new every day.

ARP is an interesting topic when it comes to the PUMA 6 and spawned a lengthy conversation on the topic alone with some theories coming out of it. We know from a users tests that ARP exhibits the same latency issues as TCP etc, as he was able to determine that his node was sending packets every 1-15ms on a clean modem, on a PUMA 6 he was seeing spikes, which would eventually taper off, like it was playing catch up to empty the buffer. 

His theory is that a lightly loaded CMTS would not exhibit the same level of issue as the amount of Broadcasted ARP packets would not be as high and the catch up process wouldn't be as loaded, thus connection are less delayed.

We know that the PUMA 6 issue seems to in most cases have a direct relation with the amount of bonded downstream channels, which may be something to down with CPU load (at a guess as ARP doesn't care about channels), but a busy CMTS with CPU load of bonded channels.... Maybe... It's one of the better theories I've read and may go to explain varying levels from users... Then again, it might not 

[boltedenergy]

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@horseman wrote:

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Guybrush85 wrote:.....Virgin didn't develop this to try and hide the behaviour, this was done by Arris/Intel and is actually a fix to ICMP traffic moving it to the Packet Processor and was done before TCP/UDP/ARP etc etc was known to be an issue.

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........At least it will stop people posting pings and BQM's all the time  *ahem* 

However some TCP/UDP resource issues (and specifically ARP cache/timeout issues) were reported during past SuperHub testing back in at least 2013 so before SH2AC Trials and current SH3 Puma6/ICMP BQM hysterics.  

As VM (public limited Beta Trials) were restricted (and in fact an ARP issue was recorded on first SH2/VMDG485 just after Apr2013 but the forum has been subsequently deleted) then we can't publish any proof (or absence to contrary) of what was forwarded via Netgear and/or to Texas/Intel other than some replies from VM CPE Firmware group that essentially(paraphrased) said the issues were "a limitation and commensurate with cost/limitations of a (implied cheap and cheerless) domestic router".    😛

That's why (after the previous SH/VMDG280, SH1/VMDG480 debacles in 2009/10) the usual user community began emphasising that VM Hubs were "get you going cheap starter devices and to use ModemMode and 3rd party routers to provide additional functionality"

Obviously there's always a "balance" between "cost/time" of both hardware and firmware versions in addressing/resolving functional and usability issues on all hubs which is why I suspect last public firmware release of SH3 9.1.116V halted back in mid 2016. 

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What i'm questioning is why the new '' firmware is taking so long to get to general release? Is there something majorly wrong with it? If not why is it still in trial?

At this rate by the time it leaves trial we might be beyond an SH4... so what's the point?

[Guybrush85]

The best I can comment (given the whole NDA thing) is that forum members within this thread have not made any suggestion that the new firmware has any faults, so put it down to Virgin being slow... As usual.

[falconevo]

That is nonsense, the 'V' version of the Intel firmware which is the one currently in testing and deployment is still subject to easy DOS attacks, poor UDP and TCP performance and just generally being a piece of trash as a modem/router.

The UDP/TCP and DOS issue is not fixed in the 'V' version of the firmware, however the ICMP (Ping) responses have been moved to the hardware acceleration which makes graphs look pretty and nothing else. UDP and TCP are still poor and it DOES affect gaming.

As for a fix, the DSL Reports thread shows some promise with 'Arris' being a main distributor of the PUMA6/7 chipset having an updated firmware version on route. Difficult to say what this fixes but the DOS based CVE will be going public soon if it is not addressed.

Imagine that, all VirginMedia modem/routers on their network susceptible to a very easy DOS. Imagine all the script kiddies that can't wait to get their hands on that information.

[PhilHornby]

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boltedenergy wrote:

What i'm questioning is why the new '' firmware is taking so long to get to general release? Is there something majorly wrong with it? If not why is it still in trial?

At this rate by the time it leaves trial we might be beyond an SH4... so what's the point?

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 Maybe they're going to bundle something else into it? ... like a KRACK fix, for example

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falconevo wrote:
That is nonsense, the 'V' version of the Intel firmware which is the one currently in testing and deployment 

Do you mean 9.1.116BA3 ? 

The UDP/TCP and DOS issue is not fixed in the 'V' version of the firmware, however the ICMP (Ping) responses have been moved to the hardware acceleration which makes graphs look pretty and nothing else. 

Well I think having ICMP working properly is useful...
...you can now see, for example, that I have a Samknows White Box in place. Previously, it was hidden behind the 'sea of yellow'.

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[Guybrush85]

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@falconevo wrote:
That is nonsense, the 'V' version of the Intel firmware which is the one currently in testing and deployment is still subject to easy DOS attacks, poor UDP and TCP performance and just generally being a piece of trash as a modem/router.

The UDP/TCP and DOS issue is not fixed in the 'V' version of the firmware, however the ICMP (Ping) responses have been moved to the hardware acceleration which makes graphs look pretty and nothing else. UDP and TCP are still poor and it DOES affect gaming.

As for a fix, the DSL Reports thread shows some promise with 'Arris' being a main distributor of the PUMA6/7 chipset having an updated firmware version on route. Difficult to say what this fixes but the DOS based CVE will be going public soon if it is not addressed.

Imagine that, all VirginMedia modem/routers on their network susceptible to a very easy DOS. Imagine all the script kiddies that can't wait to get their hands on that information.

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What I meant is that the firmware hasn't introduced any bugs from the current one in public use.

As for the DOS, it's hardly been a secret has it? https://www.theregister.co.uk/2017/08/09/intel_puma_modem_woes/

I don't seem to have read about any major attacks in as many months as it's been out. Plus, any 'booter' (to generalise the word) worth it's salt would be able to knock any home connection off, regardless of the Puma issue. So whilst a pile of  it's not causing day to day issues like the latency is.

So to the point I was trying to make to Bolt... based on things fixed in the firmware known to the public, it's still a better place to be in the interim.